Frequency analysis of task evoked pupillary response and eye-movement

Abstract

This paper describes the influence of eye blinks on frequency analysis and power spectrum difference for task-evoked pupillography and eye-movement during an experiment which consisted of ocular following tasks and oral calculation tasks with three levels of task difficulty: control, 1×1,and 1×2 digit oral calculation.The compensation model for temporal pupil size based on MLP (multi layer perceptron) was trained to detect a blink and to estimate pupil size by using blinkless pupillary change and artificial blink patterns. The PSD (power spectrum density) measurements from the estimated pupillography during oral calculation tasks show significant differences, and the PSD increased with task difficulty in the area of 0.1 - 0.5Hz and 1.6 - 3.5Hz, as did the average pupil size.The eye-movement during blinks was corrected manually, to remove irregular eye-movements such as saccades. The CSD (cross spectrum density) was achieved from horizontal and vertical eye-movement coordinates. Significant differences in CSDs among experimental conditions were examined in the area of 0.6 - 1.5 Hz. These differences suggest that the task difficulty affects the relationship between horizontal and vertical eye-movement coordinates in the frequency domain.